Parasites of graylings (Thymallidae: Thymallus) from the northern continental coast of the Okhotsk Sea

Abstract

For the first time, generalized data on parasites of two subspecies of arctic grayling (Thymallus arcticus pallasi and Th. a. mertensi) from the largest salmon rivers of the northern coast of the Okhotsk Sea, as the Taui, Yama and Gizhiga, are presented. In total, 39 species of parasites are found including 38 helminth species belonging to 26 genera, 19 families, 5 classes and 3 types (Plathelminthes, Nemathelminthes, and Acanthocephales), and 1 parasitic copepod (Crustacea; Arthropoda). Among the flatworms, trematodes have the highest species diversity — 19 species belonged to 8 genera of 6 families, and cestodes are presented by 6 species (6 genera of 5 families). Nematodes are presented by 8 species (8 genera of 5 families), and acanthocephalans — by 5 species (4 genera, 3 families, 2 classes). The graylings parasites are distributed with 2 ecological groups: the freshwater parasites including 29 species (4 cestodes, 16 trematodes, 5 nematodes, 3 acanthocephalans, and 1 copepod) and the marine parasites including 10 species (2 cestodes, 3 trematodes, 3 nematodes, and 2 acanthocephalans). Th. a. mertensi from the Taui River basin is distinguished by the highest diversity of parasites (32 species), their high diversity is observed for the same species from the Gizhiga (20 species), and for Th. a. pallasi from the Yama (24 species), as well. More than a half of helminths (22 species) are noted by medical and veterinary importance and/or are able to spoil organoleptic properties of the seafood.

Keywords

• гельминты
• ракообразные
• хариус
• лососевые реки
• северное побережье охотского моря